John Deere Maintenance Monday: Tier 4 emission standards

Ed in Virginia says he's heard bits and pieces about tier 4 emission standards coming out for tractors, and is curious what it's all about.

John Deere Spokesman Barry Nelson says the Environmental Protection Agency set higher standards for diesel engine exhaust to help clean up the air. Manufacturers are going through phases to change the engines on large row crop tractors.

"Right now we're in a phase called "interim tier 4". And interim tier 4 is not the final tier 4, which will happen in 2014, but it reduces particulate matter, it just is a cleaner burning engine," says Nelson. "For our customers we have a solution where it's a cleaner burning engine but we're still getting the fuel efficiency that they expect, the power and performance they expect, so that's been our challenge and it's been quite an investment from the company."

Diesel engine manufacturers are using one of two methods to meet the tighter emission standards. One is exhaust gas recirculation which requires a filter in the exhaust system. The other is selective catalytic reduction, or SCR, which uses a mixture of urea and de-ionized water in a post-combustion catalytic chamber.

"We have an exhaust gas recirculation-type engine, we also have a variable geometry turbo in it. It operates more efficiently, but in order to meet that interim tier 4 standard, we also had to add a larger filter, kind of the final clean-up for these engines," says Nelson. "That way we did not have to go with the urea solution, which some of our competitors do, because our customers told us they don't want to mess with a second fluid."

Compact tractors aren't impacted as much by the new emissions standards since many are already in compliance. Other models may need only minor engine modifications.